Dose rate modulated stereotactic radio surgery

ABSTRACT

The present disclosure relates to methods and systems for radiotherapy. Embodiments of the present disclosure may receive a medical image including images of a target and an organ at risk (OAR). Some embodiments may also receive a target dose and a constraint on an OAR dose. Some embodiments may also generate a dose application plan based on the target dose and the constraint. Generation of the dose application plan may include determining a placement of an arc along which radiation is to be applied based on the target dose and a location of the target; dividing the arc into a plurality of segments; determining a dose rate associated with each segment; calculating a predicted OAR dose based on the determined dose rate; and comparing the predicted OAR dose with the constraint on the OAR dose to determine whether the predicted OAR dose satisfies the constraint on the OAR dose.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 14/472,317, filed Aug.28, 2014, the entire content of which is incorporated herein byreference.

TECHNICAL FIELD

This disclosure relates generally to radiation therapy or radiotherapy.More specifically, this disclosure is directed to systems and methodsfor dose planning in radiotherapy.

BACKGROUND

Radiotherapy is used to treat tumors in mammalian tissue, such as thebrain. One such radiotherapy technique is Stereotactic Radiosurgery(SRS), by which a high dose of radiation is delivered with highprecision over a short course of treatment to a lesion localizedrelative to a three-dimensional reference system. During SRS, multipleradiation beams are directed towards a target, such as a tumor, fromdifferent angles. These radiation beams converge at an isocenter. Tissuelocated at the isocenter receives a high dose while the surroundingareas receive relatively lower doses. Therefore, it is critical for anSRS system to deliver doses to a volume that conforms to the shape ofthe target. In this way, the target receives the required dose and thedose received by the surrounding tissue, often called the organ at risk(OAR), can be minimized.

In certain cases, the target may be surrounded by OARs that may besensitive to radiation. As a result, the doses received by these OARshave to be limited to a predetermined level. Such limitations on thedoses received by the OARs, often called constraints, need to besatisfied during treatment planning.

The constraints may be satisfied by manipulating the placement of thebeam source. In an SRS system the beam source is often rotated along anarc, where the placement of the beam source is referred to as arcplacement. In those instances where a tumor is close to critical OARs orwhere a tumor has a noncircular shape, manipulation of arc placementalone may not be able to satisfy the constraints.

One way of treating a noncircular or irregular shaped tumor is tocombine multiple beam focus areas, also referred to as isocenters, intoa noncircular or irregular shape that conforms to the shape of thetumor. FIGS. 1A-1C illustrate the concept of this method. As shown inFIGS. 1A and 1B, an isocenter (e.g., 10 or 20) associated with a groupof arcs (e.g., arc group [12A, 12B] or [22A, 22B]) may have a circular(e.g., in a 2D image) or spherical (e.g., in a 3D image) shape. To mapthe elongated oval shape of a target 32 shown in FIG. 1C, isocenters 10and 20 may be combined (e.g., by combining their associated groups ofarcs) to form a combined isocenter (e.g., 30) that conforms to the shapeof the target.

SUMMARY

Certain embodiments of the present disclosure relate to a radiotherapysystem. The radiotherapy system may include a memory storing computerexecutable instructions and a processor device communicatively coupledto the memory. The processor device may be configured to execute thecomputer executable instructions for receiving a medical image of apatient. The medical image may include images of a target and an organat risk (OAR). The processor device may also be configured to executethe computer executable instructions for receiving a target dose to bereceived by the target and a constraint on an OAR dose to be received bythe OAR. In addition, the processor device may be configured to executethe computer executable instructions for generating a dose applicationplan based on the target dose and the constraint on the OAR dose.Generating the dose application plan may include determining a placementof an arc along which radiation is to be applied based on the targetdose and a location of the target and dividing the arc into a pluralityof segments. Generating the dose application plan may also includedetermining a dose rate associated with each segment and calculating apredicted OAR dose based on the determined dose rate associated witheach segment. In addition, generating the dose application plan mayinclude comparing the predicted OAR dose with the constraint on the OARdose to determine whether the predicted OAR dose satisfies theconstraint on the OAR dose.

Certain embodiments of the present disclosure relate to a method,implemented by a processor device, for dose planning in a radiotherapysystem. The method may comprise receiving a medical image of a patient.The medical image may include images of a target and an organ at risk(OAR). The method may also comprise receiving a target dose to bereceived by the target and a constraint on an OAR dose to be received bythe OAR. In addition, the method may comprise generating a doseapplication plan based on the target dose and the constraint on the OARdose. Generating the dose application plan may include determining aplacement of an arc along which radiation is to be applied based on thetarget dose and a location of the target and dividing the arc into aplurality of segments. Generating the dose application plan may alsoinclude determining a dose rate associated with each segment andcalculating a predicted OAR dose based on the determined dose rateassociated with each segment. In addition, generating the doseapplication plan may include comparing the predicted OAR dose with theconstraint on the OAR dose to determine whether the predicted OAR dosesatisfies the constraint on the OAR dose.

Additional objects and advantages of the present disclosure will be setforth in part in the following detailed description, and in part will beobvious from the description, or may be learned by practice of thepresent disclosure. The objects and advantages of the present disclosurewill be realized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only, andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which constitute a part of thisspecification, illustrate several embodiments and, together with thedescription, serve to explain the disclosed principles.

FIGS. 1A-1C illustrate a concept for combining isocenters.

FIG. 2A illustrates an exemplary radiotherapy system, according to someembodiments of the present disclosure.

FIG. 2B illustrates an exemplary radiotherapy device, according to someembodiments of the present disclosure.

FIG. 2C illustrates an exemplary data processing device used in theradiotherapy system of FIG. 2A, according to some embodiments of thepresent disclosure.

FIG. 3A illustrates an exemplary radiation beam shaper of theradiotherapy device, according to some embodiments of the presentdisclosure.

FIG. 3B illustrates an exemplary collimator of the radiotherapy device,according to some embodiments of the present disclosure.

FIG. 4 illustrates an exemplary dose planning method with reference to a2D medical image, according to some embodiments of the presentdisclosure.

FIG. 5 illustrates an exemplary dose planning method with reference to a3D medical image, according to some embodiments of the presentdisclosure.

FIG. 6 is a flowchart of an exemplary dose planning method, according tosome embodiments of the present disclosure.

FIG. 7 is a flowchart of an exemplary subroutine of the dose planningmethod of FIG. 6, according to some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Exemplary embodiments are described with reference to the accompanyingdrawings. Wherever convenient, the same reference numbers are usedthroughout the drawings to refer to the same or like parts. Whileexamples and features of disclosed principles are described herein,modifications, adaptations, and other implementations are possiblewithout departing from the spirit and scope of the disclosedembodiments. Also, the words “comprising,” “having,” “containing,” and“including,” and other similar forms are intended to be equivalent inmeaning and be open ended in that an item or items following any one ofthese words is not meant to be an exhaustive listing of such item oritems, or meant to be limited to only the listed item or items. And thesingular forms “a,” “an,” and “the” include plural references unless thecontext clearly dictates otherwise.

Systems and methods consistent with the present disclosure are directedto Stereotactic Radiation Surgery (SRS), and in particular, to improvethe flexibility and functionality of SRS technique in radiationtreatment. In addition to controlling arc placement, embodiments of thepresent disclosure can divide a single arc into a plurality of segmentsor sub-arcs, and apply different dose rates for each segment. Theradiation beam shape may also be controlled such that each arc may havedifferent beam shapes. Systems and methods consistent with the presentdisclosure may also be used for other isocentric radiation treatments.

FIG. 2A illustrates an exemplary radiotherapy system 100, according tosome embodiments of the present disclosure. Radiotherapy system 100 mayinclude a dose planning module 112 for generating a dose applicationplan, an optimization engine 114 for fine-tuning the dose applicationplan, an image acquisition device 122 for acquiring one or more medicalimages of a patient, a database 124 for storing the medical images, doseapplication information, etc., and a radiotherapy device 130 forperforming radiation treatment in accordance with the dose applicationplan.

As shown in FIG. 2A, dose planning module 112 may communicate withdatabase 124 to receive planning data stored therein. The planning datamay include patient specific information such as age, gender, tumorsize, etc. The planning data may also include medical images such asMagnetic Resonance Imaging (MRI) images and Computed Tomography (CT)images of the patient showing internal structure of the anatomicalportion under treatment.

The medical images may be provided by one or more image acquisitiondevice 122, including the same or different devices. Image acquisitiondevice 122 may include an MRI imaging device, a CT imaging device, orother medical imaging devices for obtaining one or more medical imagesof a patient. Image acquisition device 122 may provide the medicalimages to radiotherapy device 130 and/or database 124. In someembodiments, the medical images may be preprocessed by, for example,image acquisition device 122 to segment a target (e.g., a tumor). One ormore OARs may also be segmented by image acquisition device 122. Inthese embodiments, image acquisition device 122 may provide the medicalimages as well as the segmentation information to database 124, and doseplanning module 112 may receive the medical images and the segmentationinformation from database 124. In other embodiments, segmentation of thetarget and/or OARs may be performed by dose planning module 112. Inthese embodiments, image acquisition device 122 may provide the medicalimages to database 124, and dose planning module 112 may segment themedical images obtained from database 124.

The planning data stored in database 124 may be obtained fromradiotherapy device 130. In some embodiments, the planning data may becollected from multiple radiotherapy devices, or retrieved from a remotelocation, such as a radiotherapy data repository or a data center. Doseplanning module 112 may use the planning data to generate a doseapplication plan to be implemented by radiotherapy device 130 to deliverradiation treatment to a patient.

Dose planning module 112 may communicate with optimization engine 114 toperform dose plan optimization. For example, dose planning module maysend an initial dose application plan to optimization engine 114.Optimization engine 114 may fine-tune the initial dose application planto maximize the dose received by the target and minimize the dosereceived by the OARs. After optimization, the optimized dose applicationplan may be returned to dose planning module 112 and may be retrieved byradiotherapy device 130 to deliver treatment to a patient.

In some embodiments, dose planning module 112 and optimization engine114 may be implemented in a single data processing device 110. Forexample, dose planning module 112 and optimization engine 114 may beimplemented as different software programs operating on the samehardware device, as will be described in greater detail later withrespect to FIG. 2C. In some embodiments, optimization engine may beembedded into dose planning module 112. For example, optimization engine114 may be implemented as a sub-device of a dose planning device or asub-routine of a dose planning software application. In someembodiments, dose planning module 112 and optimization engine 114 may beimplemented as separate standalone modules.

In some embodiments, radiotherapy device 130 and dose planning module112 may be located in the same medical facility. In some otherembodiments, radiotherapy device 130 may be remote with respect to doseplanning module 112 (e.g., located at different locations in the same ordifferent medical facilities) and the data communication betweenradiotherapy device 130 and dose planning module 112 may be carried outthrough a network. The network may include an internal or externalnetwork (e.g., Internet). Similarly, dose planning module 112 anddatabase 124, dose planning module 112 and optimization engine 114,database 124 and radiotherapy device 130, image acquisition device 122and radiotherapy device 130, database 124 and image acquisition device122 may also be located locally or remote to each other, and maycommunicate over an internal or external network.

FIG. 2B illustrates an exemplary configuration of radiotherapy device130 (e.g., a linear accelerator), according to some embodiments of thepresent disclosure. Using a linear accelerator 130, a patient 42 may bepositioned on a patient table 43 to receive the radiation dose accordingto a dose application plan (e.g., determined by dose planning module 112or further optimized by optimization engine 114). Linear accelerator 130may include a radiation head 45 that generates a radiation beam 46. Theentire radiation head 45 may be rotatable around a horizontal axis 47.In addition, below the patient table 43 there may be provided a flatpanel scintillator detector 44, which may rotate synchronously withradiation head 45 around an isocenter 41. The intersection of the axis47 with the center of the beam 46, produced by the radiation head 45, isusually referred to as the “isocenter”. The patient table 43 may bemotorized so that the patient 42 can be positioned with the tumor siteat or close to the isocenter 41. The radiation head 45 may rotate abouta gantry 48, to provide patient 42 with a plurality of varying dosagesof radiation according to the dose application plan.

FIG. 2C illustrates an exemplary data processing device 110. As shown inFIG. 2C, data processing device 110 may include a processor device 250,a memory or storage device 260, a communication interface 270, an inputdevice 282, and an output device 284. Memory/storage device 260 maystore computer executable instructions, such as operating system 262 anddose planning/optimization software 264. Processor device 250 may becoupled to memory/storage device 260 and configured to execute thecomputer executable instructions stored thereon. For example, processordevice 250 may execute dose planning/optimization software 264 toimplement functionalities of dose planning module 112 and/oroptimization engine 114. Processor device 250 may communicate withdatabase 124 through communication interface 270 to send/receive datato/from database 124. Although only one database 124 is shown in FIG.2C, one skilled in the art would appreciate that database 124 mayinclude a plurality of devices located either in a central ordistributed manner.

Processor device 250 may include one or more general-purpose processingdevices such as a microprocessor, central processing unit (CPU), or thelike. More particularly, processor device 250 may be a complexinstruction set computing (CISC) microprocessor, reduced instruction setcomputing (RISC) microprocessor, very long instruction Word (VLIW)microprocessor, a processor implementing other instruction sets, orprocessors implementing a combination of instruction sets. Processordevice 250 may also be one or more special-purpose processing devicessuch as an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), a digital signal processor (DSP), aSystem on a Chip (SoC), or the like. As would be appreciated by thoseskilled in the art, in some embodiments, processor device 250 may be aspecial-purpose processor, rather than a general-purpose processor.

Memory/storage device 260 may include a read-only memory (ROM), a flashmemory, a random access memory (RAM), a static memory, etc. In someembodiments, memory/storage device 260 may include a machine-readablestorage medium. While the machine-readable storage medium as anexemplary embodiment may be a single medium, the term “machine-readablestorage medium” should be taken to include a single medium or multiplemedia (e.g., a centralized or distributed database, and/or associatedcaches and servers) that store one or more sets of instructions/data.The term “machine-readable storage medium” shall also be taken toinclude any medium that is capable of storing or encoding a set ofinstructions for execution by the machine and that cause the machine toperform any one or more of the methodologies of the present disclosure.The term “machine readable storage medium” shall accordingly be taken toinclude, but not be limited to, solid-state memories, and optical andmagnetic media.

Communication interface 270 may include a network adaptor, a cableconnector, a serial connector, a USB connector, a parallel connector, ahigh-speed data transmission adaptor such as fiber, USB 3.0,thunderbolt, etc., a wireless network adaptor such as WiFi adaptor,telecommunication (3G, 4G/LTE etc.) adaptor, etc. Communicationinterface 270 may also include communication interface with radiotherapydevice 130. Processor device 250 may communicate with database 124,radiotherapy device 130, or other devices or systems via communicationinterface 270. Input device 282 may include a keyboard, a mouse, atouchscreen, or other suitable devices for receiving information inputby a user. Output device 284 may include a display, a printer, or othersuitable devices for outputting information to the user.

Data processing device 110 may be in communication with radiotherapydevice 130. As noted above, radiotherapy device 130 may be a deviceconfigured to deliver radiation therapy. Radiotherapy device 130 mayinclude a radiation source and employ a radiation beam shaper to controlthe shape and/or size of the radiation beam emitted by the radiationsource.

FIG. 3A illustrates an exemplary radiation beam shaper 302, according tosome embodiments of the present disclosure. Radiation beam shaper 302may be installed on a collimator 310 (e.g., shown in FIG. 3B) andtowards patient 42. Radiation beam shaper 302 may include an opening 304to allow passage of a radiation beam. Opening 304 may be a cone-shapedopening, which may be sized and shaped to generate a radiation beamhaving a cone-like shape. Radiation beam shaper 302 may be used tocontrol the size of the radiation beam passing through opening 304. Forexample, radiation applied along each arc may employ a particular sizedradiation beam, and the size of radiation beams applied along differentarcs may be different. The radiation beam size may be controlled byswitching radiation beam shapers having different opening sizes. In someembodiments, opening 304 may be less than 5 cm, or may be less than 1 cmin diameter. For example, opening 304 may be 1 mm-5 mm in diameter.Other sizes may also be used.

FIG. 3B illustrates an exemplary collimator 310. Collimator 310 mayinclude a mounting opening 312 through which a radiation beam shaper(e.g., 302) may be installed. For example, the radiation beam shaper maybe installed onto collimator 310 through interlocking, fastening,screwing, snap-fitting, or other suitable method.

In a radiotherapy treatment, the dose planning stage can be divided intotwo parts. The first part may include the segmentation of a target, suchas a tumor. In some embodiments, the first part may also include thesegmentation of OARs. As noted above, the segmentation may be performedby image acquisition device 122 or by dose planning module 112. Forexample, image acquisition device 122 or dose planning module 112 mayidentify a target volume in a medical image by contouring the target ineach 2D layer or slice of the medical image and combining the contoursof multiple 2D layers or slices. Similarly, image acquisition device 122or dose planning module 112 may identify an OAR volume in a medicalimage by contouring the OAR in each 2D layer or slice of the medicalimage and combining the contours of multiple 2D layers or slices. Thesegmentation of the target/OAR may be performed automatically ormanually.

After the segmentation stage, the second part of the dose planning mayinclude creating a dose application plan. The dose application plan mayindicate the specific steps to apply radiation beams, normally frommultiple angles, to the target under treatment. The dose applicationplan may include arc placement, dose rate, and/or radiation beam shape.The arc placement may indicate the positions or angles from whichradiation is to be applied. The dose rate may indicate the desiredamount of dose, normally measured by the beam-on time. The radiationbeam shape may be controlled by a radiation beam shaper (e.g., 302).

FIG. 4 illustrates an exemplary dose planning method with reference to a2D medical image. In FIG. 4, a target 410 and an OAR 420 may besegmented by image acquisition device 122 or dose planning module 112,as noted above. FIG. 4A shows multiple arcs, for example, 430A, 430B,430C, and 430D, from which radiation may be applied. For example,radiation head 45 may rotate along arc 430A and apply radiation at oneor more points along arc 430A. The placement of the arcs may bedetermined by dose planning module 112 based on the size and location ofthe target and/or the OAR, the desired dose to be received by thetarget, the dose constraint to be satisfied with respect to the OAR,and/or any other parameter known to one of ordinary skill in the art. Insome embodiments, dose planning module 112 may determine the placementof the arcs, dose rate to be applied along each arc, and the radiationbeam shape to be used on each arc. In some embodiments, dose planningmodule 112 may also determine a weighting factor associated with eacharc. For example, in FIG. 4, arc 430A covers a portion of OAR 420. Doseplanning module 112 may assign a weighting factor to arc 430A to reducethe dose received by OAR 420 when radiation is applied along arc 430A.Similarly, dose planning module 112 may assign a weighting factor to arc430B to increase the dose received by target 410 when radiation isapplied along arc 430B. In this manner, the dose applied to target 410and OAR 420 can be controlled.

In some cases, the combination of arc placement, dose rate (as modifiedby weighting factors), and radiation beam shape may not be able tosatisfy the dose constraint. For example, in the case shown in FIG. 4, acertain area in target 410 may not be able to receive enough dose if aweighting factor is assigned to arc 430A to satisfy the dose constraintimposed by OAR 420. On the other hand, if the weighting factor isincreased to satisfy the dose requirement of target 410, the doseconstraint imposed by OAR 420 may not be satisfied. In this case, doseplanning module 112 may divide arc 430A into multiple segments andassign different dose rate to different segments. For example, doseplanning module 112 may divide arc 430A into segment 432 and segment434. In segment 432, the dose rate may be decreased to a lower level toreduce the radiation received by OAR 420. In segment 434, the dose ratemay be increased to a higher level to satisfy the dose requirement oftarget 410. In this way, a dose application plan may be created tosatisfy both the dose requirement of target 410 and dose constraint ofOAR 420.

Once dose planning module 112 divides one or more arcs into multiplesegments and assigns different dose rates (e.g., by assigning differentweighting factors) to different segments, dose planning module 112 maythen calculate a predicted OAR dose based on the assigned dose rateassociated with each segment. For example, dose planning module 112 maycalculate a dose distribution within the volume of target 410 and OAR420 based on the arc placement, arc segments, dose rates, and radiationbeam shape as determined in the dose application plan. The dosedistribution may be calculated, for each voxel of target 410 or OAR 420,by summing up the dose received from each individual radiation beamprescribed by the dose application plan, taking into consideration thedose rate (e.g., weighting factor) associated with each arc segment andradiation beam shape associated with each arc segment. Dose planningmodule 112 may then compare the predicted OAR dose with the constrainton the OAR dose to determine whether the constraint is satisfied.

If the constraint is not satisfied, the dose planning module 112 mayrevise one or more parameters in the dose application plan. For example,dose planning module 112 may revise the arc placement by, for example,adding a new arc, removing an existing arc, changing the position,direction, length, and/or curvature of an arc, etc. Dose planning module112 may also revise the segmentation of an arc. For example, doseplanning module 112 may divide an arc into a different number ofsegments, assign a different length to a segment, etc. In addition, doseplanning module 112 may revise the dose rate associated with eachsegment. For example, dose planning module 112 may increase or decreasethe dose rate assigned to a segment. Moreover, dose planning module 112may revise the radiation beam shape. For example, dose planning module112 may assign a different beam shape to an arc or an arc segment. Thedifferent radiation beam shape, including the shape of the radiationbeam and the size of the radiation beam, may be achieved by employingradiation beam shapers having openings of different shapes and/or sizes.The revision may be an iterative process, in which multiple rounds ofrevisions may be carried out by dose planning module 112 until theresulting dose application plan satisfies the constraint.

If the constraint is satisfied, then dose planning module 112 mayprovide the dose application plan with the determined placement of thearc, the arc segments, and the dose rate associated with each segmentsto radiotherapy device 130 for performing radiation treatment. In someembodiments, dose planning module 112 may provide the dose applicationplan to a user (e.g., physician, doctor, etc.) for furtherconsideration.

In some embodiments, dose planning module 112 may provide the doseapplication plan to optimization engine 114 for optimization. The doseapplication plan determined by dose planning module 112 may be aninitial plan that satisfies both the target dose requirement and the OARdose constraints. Optimization engine 114 may fine-tune the initial planand generate an optimized dose application plan. For example,optimization engine 114 may calculate predicted target dose and OAR doseusing different arc placements, arc segmentations, and/or radiation beamshapes and compare the calculation results. In some embodiments, a planhaving the lowest OAR dose may be selected as the optimized plan. Insome embodiments, a plan having a balanced high target dose and low OARdose may be selected as the optimized plan. In some embodiments, a planhaving the highest target dose and satisfying the OAR dose constraintmay be selected as the optimized plan. A person skilled in the art willunderstand that other criteria may also be adopted in the selection ofthe optimized plan. Once the optimized plan is finalized, the plan maybe retrieved or sent to radiotherapy device 130 for implementation.

FIG. 5 illustrates an exemplary dose planning method with reference to a3D medical image. In FIG. 5, the directions along which arcs 440A and450A may be different. This may be achieved by rotating patient table43. For example, radiation head 45 may apply radiation along arcs 440Aand 440B while patient table 43 is at a first position, and may applyradiation along arcs 450A and 450B while patient table 43 rotates to asecond position. The rotation of patient table 43 may also be consideredas a parameter in determining arc placement and/or arc segmentation. Forexample, dose planning module 112 may generate a dose application planhaving arcs extending along different directions, and divide one or morearcs into multiple segments and assign individual dose rate to eachsegment.

FIG. 6 is a flowchart of an exemplary dose planning method 600,according to some embodiments of the present disclosure. At step 602,dose planning module 112 may receive a medical image (e.g., the medicalimage shown in FIG. 4) of a patient from database 124. The medical imagemay be generated by image acquisition device 122 and may include imagesof a target (e.g., target 410) and an OAR (e.g., OAR 420).

At step 604, dose planning module 112 may receive a target dose to bereceived by target 410 and a constraint on an OAR dose to be received byOAR 420. The target dose and the constraint on the OAR dose may bereceived from a user inputted through input device 282.

At step 606, dose planning module 112 may determine a dose applicationplan based on the target dose and the constraint on the OAR dose. Step606 is described in greater detail in FIG. 7.

Referring to FIG. 7, step 606 may include a substep 702, in which doseplanning module 112 and/or a user may determine a placement of an arc onwhich radiation is to be applied based on the target dose and a locationof the target. For example, in some embodiments, a user may determineplacement of arcs 430A, 430B, 430C, and 430D such that radiation head 45may rotate along these arc to apply radiation. In some embodiments, doseplanning module 112 may determine placement of these arcs. At substep704, dose planning module 112 may divide one or more arcs, such as arc430A, into a plurality of segments, such as segments 432 and 434. Atsubstep 706, dose planning module 112 may determine a dose rateassociated with each arc or arc segment. For example, each arc segmentmay be assigned an individual dose rate and different arc segments, evenon the same arc, may be assigned different dose rates. At substep 708,dose planning module 112 may calculate a predicted OAR dose based on thedetermined dose rate associated with each arc or arc segment. Forexample, dose planning module 112 may calculate an individual OAR doseresulting from each individual arc or arc segment and sum up theindividual OAR dose to arrive at a predicted OAR dose. At substep 710,dose planning module 112 may compare the predicted OAR dose and theconstraint on the OAR dose to check if the dose application plan satisfythe constraint (at substep 712). If the constraint is satisfied, processproceeds to substep 714, in which dose planning module 112 may providethe dose application plan to a user for further consideration. In someembodiments, dose planning module 112 may also provide the doseapplication plan to radiotherapy device 130 for performing radiationtreatment. If the constraint is not satisfied, process proceeds tosubstep 716, in which dose planning module 112 may revise one or moreparameters such as the arc placement, the segmentation of an arc, and/orthe dose rate associated with each arc segment. Accordingly, process mayproceeds to any one of substep 702, 704, or 706.

Various operations or functions are described herein, which may beimplemented or defined as software code or instructions. Such contentmay be directly executable (“object” or “executable” form), source code,or difference code (“delta” or “patch” code). Software implementationsof the embodiments described herein may be provided via an article ofmanufacture with the code or instructions stored thereon, or via amethod of operating a communication interface to send data via thecommunication interface. A machine or computer readable storage mediummay cause a machine to perform the functions or operations described,and includes any mechanism that stores information in a form accessibleby a machine (e.g., computing device, electronic system, and the like),such as recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, and the like). A communication interfaceincludes any mechanism that interfaces to any of a hardwired, wireless,optical, and the like, medium to communicate to another device, such asa memory bus interface, a processor bus interface, an Internetconnection, a disk controller, and the like. The communication interfacecan be configured by providing configuration parameters and/or sendingsignals to prepare the communication interface to provide a data signaldescribing the software content. The communication interface can beaccessed via one or more commands or signals sent to the communicationinterface.

The present invention also relates to a system for performing theoperations herein. This system may be specially constructed for therequired purposes, or it may comprise a general purpose computerselectively activated or reconfigured by a computer program stored inthe computer. Such a computer program may be stored in a computerreadable storage medium, such as, but not limited to, any type of diskincluding floppy disks, optical disks, CDROMs, and magnetic-opticaldisks, read-only memories (ROMs), random access memories (RAMS), EPROMs,EEPROMs, magnetic or optical cards, or any type of media suitable forstoring electronic instructions, each coupled to a computer system bus.

The order of execution or performance of the operations in embodimentsof the invention illustrated and described herein is not essential,unless otherwise specified. That is, the operations may be performed inany order, unless otherwise specified, and embodiments of the inventionmay include additional or fewer operations than those disclosed herein.For example, it is contemplated that executing or performing aparticular operation before, contemporaneously with, or after anotheroperation is within the scope of aspects of the invention.

Embodiments of the invention may be implemented with compute executableinstructions. The computer-executable instructions may be organized intoone or more computer-executable components or modules. Aspects of theinvention may be implemented with any number and organization of suchcomponents or modules. For example, aspects of the invention are notlimited to the specific computer-executable instructions or the specificcomponents or modules illustrated in the figures and described herein.Other embodiments of the invention may include differentcomputer-executable instructions or components having more or lessfunctionality than illustrated and described herein.

Having described aspects of the invention in detail, it will be apparentthat modifications and variations are possible without departing fromthe scope of aspects of the invention as defined in the appended claims.As various changes could be made in the above constructions, products,and methods without departing from the scope of aspects of theinvention, it is intended that all matter contained in the abovedescription and shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

What is claimed is:
 1. A system for generating a dose application planfor radiotherapy, comprising: a memory storing computer executableinstructions; a processor device communicatively coupled to the memory,wherein the processor device is configured to execute the computerexecutable instructions for: receiving a target dose for treating atarget during a radiotherapy treatment; determining a placement of anarc along which radiation is to be applied based on the target dose anda location of the target; dividing the arc into a plurality of segments;determining a dose rate associated with each segment; calculating apredicted dose to be received by an organ at risk (OAR) based on thedetermined dose rate associated with each segment; and generating thedose application plan based on the predicted dose and the dose rateassociated with each segment.
 2. The system of claim 1, wherein theprocessor device is configured to execute the computer executableinstructions for: receiving a constraint on a dose to be received by theOAR during the radiotherapy treatment; and comparing the predicted dosewith the constraint to determine whether the predicted dose satisfiesthe constraint.
 3. The system of claim 2, wherein the processor deviceis configured to execute the computer executable instructions for:providing the dose application plan with the determined placement of thearc, the plurality of segments of the arc, and the dose rate associatedwith each segment to a user when the predicted dose satisfies theconstraint.
 4. The system of claim 2, wherein the processor device isconfigured to execute the computer executable instructions for: revisingat least one of: the placement of the arc, the dividing of the pluralityof segments, or the dose rate when the predicted dose does not satisfythe constraint.
 5. The system of claim 1, wherein the processor deviceis configured to execute the computer executable instructions for:determining a radiation beam shape associated with the arc; andcalculating the predicted dose to be received by the OAR based on thedetermined dose rate associated with each segment and the radiation beamshape associated with the arc.
 6. The system of claim 5, comprising: aradiation beam shaper to control the radiation beam shape associatedwith the arc.
 7. The system of claim 6, wherein the radiation beamshaper has a cone-shaped opening.
 8. The system of claim 6, wherein theradiation beam shaper has an opening that is less than 5 cm in size. 9.The system of claim 1, wherein the processor device is configured toexecute the computer executable instructions for: determining placementof a plurality of arcs along which radiation is to be applied based onthe target dose and the location of the target; and determining aweighting factor associated with each arc.
 10. The system of claim 1,wherein the processor device is configured to execute the computerexecutable instructions for: receiving a medical image of a patient, themedical image including images of the target and the OAR; andidentifying a target volume corresponding to the target and an OARvolume corresponding to the OAR in the medical image.
 11. A method fordose planning in a radiotherapy system, the method comprising: receivinga target dose for treating a target during a radiotherapy treatment;determining a placement of an arc along which radiation is to be appliedbased on the target dose and a location of the target; dividing the arcinto a plurality of segments; determining a dose rate associated witheach segment; calculating a predicted dose to be received by an organ atrisk (OAR) based on the determined dose rate associated with eachsegment; and generating a dose application plan based on the predicteddose and the dose rate associated with each segment.
 12. The method ofclaim 11, comprising: receiving a constraint on a dose to be received bythe OAR during the radiotherapy treatment; and comparing the predicteddose with the constraint to determine whether the predicted dosesatisfies the constraint.
 13. The method of claim 12, comprising:providing the dose application plan with the determined placement of thearc, the plurality of segments of the arc, and the dose rate associatedwith each segments to a user when the predicted dose satisfies theconstraint.
 14. The method of claim 12, comprising: revising at leastone of: the placement of the arc, the dividing of the plurality ofsegments, or the dose rate when the predicted dose does not satisfy theconstraint.
 15. The method of claim 11, comprising: determining aradiation beam shape associated with the arc; and calculating thepredicted dose to be received by the OAR based on the determined doserate associated with each segment and the radiation beam shapeassociated with the arc.
 16. The method of claim 14, comprising:controlling, using a radiation beam shaper, the radiation beam shapeassociated with the arc.
 17. The method of claim 11, comprising:determining placement of a plurality of arcs along which radiation is tobe applied based on the target dose and the location of the target; anddetermining a weighting factor associated with each arc.
 18. The methodof claim 11, comprising: receiving a medical image of a patient, themedical image including images of the target and the OAR; andidentifying a target volume corresponding to the target and an OARvolume corresponding to the OAR in the medical image.
 19. Anon-transitory computer-readable medium storing non-transitoryinstructions for generating a dose application plan for radiotherapy,wherein the instructions, when executed by a processor device, cause theprocessor device to perform a method including: receiving a target dosefor treating a target during a radiotherapy treatment; determining aplacement of an arc along which radiation is to be applied based on thetarget dose and a location of the target; dividing the arc into aplurality of segments; determining a dose rate associated with eachsegment; calculating a predicted dose to be received by an organ at risk(OAR) based on the determined dose rate associated with each segment;and generating the dose application plan based on the predicted dose andthe dose rate associated with each segment.
 20. The non-transitorycomputer-readable medium of claim 19, wherein the instructions storedthereon, when executed by the processor device, cause the processordevice to perform: receiving a constraint on a dose to be received bythe OAR during the radiotherapy treatment; comparing the predicted dosewith the constraint to determine whether the predicted dose satisfiesthe constraint; providing the dose application plan with the determinedplacement of the arc, the plurality of segments of the arc, and the doserate associated with each segments to a user when the predicted dosesatisfies the constraint; and revising at least one of: the placement ofthe arc, the dividing of the plurality of segments, or the dose ratewhen the predicted dose does not satisfy the constraint.